Federal Funding Legend
This invention was produced in part using funds obtained through grant DK 21800 from the National Institutes of Health. Consequently, the federal government has certain rights in this invention.
1.Field of the Invention
The present invention relates generally to the fields of microbiology and anti-bacterial therapy. More specifically, the present invention relates to high-mannose oligosaccharides that inhibit the binding of gram-negative pathogenic bacteria to cell membranes and uses thereof.
2.Description of the Related Art
Enterobacter species are a major problem to clinicians because of their resistance to multiple drugs, including the new cephalosporins and penicillins (15), and since 1993, the incidence of these organisms in intensive care units has increased. Enterobacter cloacae is the species most frequently isolated from clinical specimens, followed by Enterobacter aerogenes and Enterobacter agglomerans (1,10,11,17). This alarming increase in multiple antibiotic resistant organisms suggests that new chemotherapeutic strategies, such as inhibition of bacterial adhesion, are necessary to control colonization or infection in infants and patients at high risk.
Bacterial attachment to mucosal surfaces is the first step in colonization and pathogenesis (2). A number of bacteria bind to host cell surfaces via a protein to carbohydrate interaction (29). Usually in these cases, the carbohydrate molecule exists as a glycolipid or glycoprotein in the plasma membrane of the host cell, and this "oligosaccharide" is recognized by proteins, called lectins, on the bacterial surface. These lectins are frequently part of the pili or fimbriae that are produced by many bacteria, especially gram-negative organisms (27).
A number of studies have investigated the interaction of enteric bacteria with various animal cells, and have shown that in many cases this binding involves recognition of mannose-containing structures on the animal cell surface by type 1 pili on the bacteria (8,9,26,27,28,29). However, the specific carbohydrate structure that is recognized by type 1 pili has either not been well defined, or varies depending on the source of the type 1 pili. Based on the ability of various mannosides to inhibit the agglutination of yeast by enteric bacteria, Firon, et al (9) concluded that the fimbrial lectins of various genera exhibit differences in sugar specificity, but all strains within a genera exhibit the same sugar specificity.
Studies by Firon et al (8) indicated that aromatic .alpha.-glycosides of mannose were more effective as inhibitors of Escherichia coli binding to epithelial cells than was .alpha.-methylmannoside. In fact, these workers demonstrated that p-nitrophenyl-.alpha.-D-mannoside was considerably better as an inhibitor than was .alpha.-methylmannoside, and methylumbelliferyl-.alpha.-mannoside was even better then the p-nitrophenyl-derivative.
There is a considerable amount of information concerning the structure of type 1 pili (16), and the type 1 fimbrial gene cluster of Escherichia coli (18,30) and Klebsiella pneumoniae (3) have been cloned. Mutant bacteria lacking the receptor binding function were as ineffective at colonizing the bladder as were mutants lacking the entire type 1 pili (18). These latter studies lend support to the hypothesis that interference with the interaction of bacterial type 1 adhesin with the high-mannose glycoprotein, either by tying up the high-mannose site or by altering the pili in some way, could provide a useful chemotherapy for these types of infections.
The prior art is deficient in the ability to effectively and consistently treat gram-negative bacterial infections. More specifically, the prior art is deficient in preventing the adhesion of pathogenic bacteria to the mucous membranes of the host cells. The present invention fulfills this long-standing need and desire in the art.